Sawdust-burning furnace



Patented July 11, 1939 2,165,802

UNITED STATES PATENT OFFICE sAWDUsT-BURNING FURNACE Arthur J. Longtin, Seattle, Wash. `Applicatifm March 15, 1937, serial No. 130,912

s claims. (c1. 122-136) This invention relates generally to furnaces and the grate. A hopper which feeds through and particularly to that class of furnace in which a roof opening for delivering fllel over the Plate saw-dust and other comminuted fuels are used 'I to the surface of the grate is indicated at II. as the heat-generating medium. As is customary in advanced saw-dust burn The principal objects of the present invention ers, the grate which I employ iS deSirahly irl the are to provide a water-jacketed type of furnace form of an open-end drawer providing closed peculiarly adapted to the specific requirements front and side walls I2 and I3, respectively, and of a wood-refuse burner and so applied, through a horizontal fuel-supporting upper wall I 4 in the employment of the water-jacketing as the which are slots or other suitable grate openings l0 water-heating plant of a circulating hot-Water I5. Removal of the grate iS permitted through l0 system, either for heating or draw-off purposes, an end opening in the furnace closed by the door or both, that the` generated heat is utilized to indicated at I5, Said door Carrying lhe CorlVerlthe fullest possible extent, that the life of the tional hinged draft gate Il Which iS Controlled furnace is prolonged in that the intense heat by a chain I8.

generated by a saw-dust burner, heat which has With respect to the Water-jacketprovisiohS of l5 heretofore been concentrated on a furnace linthe furnace, Water Chambers are provided to lie ing incapable of rapidly dissipating the same, is at each side of, above, and at the front end of rapidly conducted from the point of heat conthe combustion chamber and of these water centration, and otherwise to provide a saw-dust chambers, those laterally disposed and indicated burning furnace of generally improved and simby 20 extend vertically the full depth ofthe com- 20 plied construction. bustion chamber and horizontally approximately It is a further and particular object of my the entire length of the furnace to laterally eninvention to so adapt such Water-jacketing to close the air chamber 6 as well asthe combusa saw-dust burning furnace as to permit a prac- Jtion Chamber 5. The forwardly disposed end tical utilization or a down-draft in the travel cavity of Said` Water chambers, represented by 25 of the gases of combustion from the fire-box to 2|, iS 0f leSS depth than the Side chambers and the flue. provides a restricted throat below the same per- 'I'he foregoing and still further and more parmiti/ing escape of the Products 0f Combustionticular objects and advantages of the present From this throat, repreSehi'fed by 23, the gaSeS invention will be apparent in the course of the rise through a vertical flue duct 24 and thence 30 following description and claims, the invention through a horizontal fille duct 25 Which overleS consisting in the novel construction, adaptation, the upper Water Chamber 22 DaSS into a Smoke and combination of parts hereinafter described pipe 2B tted with a damper 23. and claimed. Hingedly suspended at the juncture of the flue In the drawingducts 24 and 25 is a gate 21 which may be em- 35 Figure 1 is a front elevational View and Fig. 2 ployed as a check-draft and which is disposed a section taken on the longitudinal median line to operate as a clean-out door for each of the thereof to illustrate a furnace constructed acflue ducts.

cording to the now preferred embodiment of the 30 denotes a cold-water inlet pipe and 3I invention. a hot-wateroutlet pipe connecting the water- 40 Fig. 3 is a transverse vertical section taken on jackets in a circulating heating or draw-off systhe jogged section line 3-3 of Fig. 2; and tem, the pipe 30 connecting with one of the side Fig. 4 is a horizontal section taken on the chambers 2|] in proximity of the lower limits jogged line II-ll of Fig. 2, the scale being reduced thereof and adjacent the rear of the furnace from that employed in the preceding views. while the pipe 3l connects with the chamber 22 45 As represented in the drawing, the furnace directly above the point of maximum heat conprovides that which is ordinary in saw-dust centration, which is to say the apex of the L- burners, a tunnel-like cavity forming a combusangle produced between the water chambers 2l tion chamber 5 at the front end and an air and 22. The upper wall of said lateral chambers chamber 6 at the rear end, the chambers being 20 and the ceiling chamber 22 have a progressive 50 separated by a shiftable grate and a sloping rise toward the outlet pipe 3| to prevent the deplate 1 suspended from fixed lugs 8 to lie above velopment of steam pockets within the Water the rear portion of the grate. Toe elements III chambers. on said plate I elevate the lower edge of the The principal objection to saw-dust burning plate and provide an interstice between the plate furnaces has been the intense concentration of 55 heat on that portion of the lire-box ceiling which lies above the point of combustion of the gases, causing warping of the ceiling plate and necessitating frequent replacement. A refractory-brick lining the heat-subtaining characteristics of Which are sufficient to withstand the excessive spot temperatures in a saw-dust burner are too costly, the commonly-used fire-brick being invariably destroyed by fusion. It is by reason of the fact that any developed down-draft still further intensies this application of heat far beyond the ability of the ordinary'wall structure to dissipate the same which accounts for the failure to have heretofore evolved any saw-dust burning furnace in which this desirable feature has been practically applied. In the few instances in which a down-draft hasbeen attempted heretofore, a more rapid depreciationfof the fire-box lining results and the partitioning walls used to effect the down-draft have burnedr'out at frequent. intervals. l

The. present invention; provideswhat; constitutes a completely water-'jacketed furnace' for householdvuse of saw-dust as' the combustible fuel, a furnace in which thechambersare so designed as .to'obtain a. rapid dissipation of heat from ,the walls tothe readily mobile and effective heat-conducting agent, Water. The life of the furnace is prolonged, the heatingiefliciency increased an-d, through 'the provision of heating tanksof large capacity indirect heat-conducting relationto the. fireat the point of maximum development .ofheatin theV latter, `this as .distingulshed from the necessarily remotelocation of coils .of small water-capacity, an abundance of hotV water is obtainedfforuse either in acircul lating heating. system or for Ldraw-off purposes,

or both.

I do not necessarily limit myself .to the structure which Iparticularly describe with reference to the illustratedpreferred embodiment and intend .that the` claims be given abreadth in their interpretation commensurate with the Ystate of the advance in the art.

What I claim, is:

1. A furnace having a Wall at the outlet endfof the combustion chamber extending from .the ceiling of the combustion chamber into proximity of but spaced from the floor of the chamber to form a down-draft delivery throat through which the products of combustion pass from the chamber and providing return-flow flue ducts leading from said throat to have the gases pass upwardly over the rear surface of the end Wall and horizontally therefrom over the upper Wall of the chamber, the furnace at the juncture of said flue ducts having an opening aligned with and common to each of the flue passages, and a chain-operated hinged door for said'opening acting as a check damper for the furnace, the positioning of said opening at the juncture of said vertical and horizontal flue ducts inalignment with both of the same permitting use of the opening as a clean-out for the kflue ducts.

2. A furnace-providing a combustion chamber of which the roof is water-jacketed for the conduction of heat and wherein the cell forming said jackethas its.lower Wall approximately horizontal and the ceilingdisposed 'at an oblique angle .thereto and" located such that the narrow end of the gure produced bysaid horizontal lower wall and oblique ceiling lies at the end of the chamber remote from'thegas-discharge end, said cell be- 3. A furnace lhaving a wall at the gas-discharge end of thev combustion" chamber Awhich extends from the roof ofthe combustion chamber into proximity 'of but spaced from the floor of the chamber to form aV down-draft delivery throat L throughwhich the products of combustion pass fromY the chamber; the upper wall of said chamber providingaJ water cell therein of which the. floor lies in a substantial horizontal planeand the ceiling rises progressively from the rear combustion-initiating end toward the forward gas-discharge4 end of the combustion chamber, said cell being provided with connections for the hot and cold water pipes of a water-circulating system,

the hot'Water connection thereof lyingin the ceiling of the cell at the deepi end of .the latter.

ARTHUR. J. LONGTIN. 

